scim has been replaced by ibus in Fedora (and most other distributions). ibus really is better, and (I suspect just like Wayne), I haven't used it in Fedora in awhile, which is why I'm not giving you an answer to your question. Not having used scim in Fedora in awhile, I just don't know the answer.

Yes, it's been a while since I used Scim. iBus works great for me. Installing the ibus-gtk package in KDE makes Firefox and GTK apps work properly. Perhaps it needs to be added as a dependency to ibus when Firefox is installed.